Dispersal of <i>Trichospilus diatraeae</i> Cherian & Margabandhu (Hymenoptera: Eulophidae) in sugar cane field

Abstract

The success of biological control programs, with parasitoids depends on the evaluation of the behavior of parasitoids in the field. Thus, dispersal of Trichospilus diatraeae Cherian & Margabandhu, 1942 (Hymenoptera: Eulophidae) was studied in a ratoon crop of sugar cane at seven months of age in Dourados, Mato Grosso do Sul State, Brazil. Ten 452-m² stands were delimited and inside them four concentric circles with radius of three, six, nine and 12 m with four, eight, 12 and 16 collection sites, respectively. Collection sites were represented by traps with one Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) pupae inside each of them. Two thousand parasitoids (44250 parasitoids ha^-1) were released at the central point, except in control plots, and the traps were collected after 48 hours. Parasitism was reduced as the distance from the release site increased with means of 12.5% at three and 2.5% at 12 m. Formicidae specimens preyed 59.0% of D. saccharalis pupae and 34.0% of these pupae were not found by parasitoids or predators because of emergence of moth. T. diatraeae females found and parasitized D. saccharalis pupae in sugar cane with seven months of ratoon up to 12 m from the release site.